The Mystery in the Window

When her teacher informs the class that Duchess, the school cat, is missing, Gracie jumps right in on the case. She is used to snooping around, but when she finds a message in the window of an old, abandoned house, she thinks it's a little too freaky. BUT ... they don't call her 'Super Spy' for nothing—she decides she is not going to be scared away. When she finds more mysterious things going on in the old house, can she get anyone to investigate with her?